In conventional siphon or downwash type of toilets, water is stored in a water tank. In use, all the water stored in the tank is flushed for discharging either the solid or the liquid excretion from the bowl. However, such large quantity of water is not always required for discharging the excretion. For example, a substantial difference should exist between the water quantity required for discharging urine and that for discharging excrement. That is, the entire quantity of water in the tank may be required for discharging the solid excrement while only a small quantity of water may suffice to discharge the urine. Therefore, there is apparent excessive waste of water with conventional toilets in that the same quantity of water is used for flushing whether solid excrement or liquid urine is to be discharged.
In view of the above, various types of water saving toilets have been introduced. Prior art water saving toilets have been directed primarily to changing the arrangement of the elements within the water tank, that is, the flushing control handle, the float ball, the discharging valve, and other elements in the tank are altered in structure so as to serve the purpose of two-stage flushing. Nevertheless, since there is no corresponding alteration in the design of the bowl structure, such water saving toilets still have the same practical problems as those encountered with conventional toilets as follows.
1. The discharging line system in conventional water saving toilets is of the single line design such that when water saving operation is performed for discharging urine, the quantity of water flowing into the bowl from the water tank must still be adequate for the water level in the bowl to rise above the point of the siphonage starting height of the single discharging line at the upper edge of the tube, that is the point corresponding to the point of the siphonage starting height of the single discharging line at the upper edge point 2A of the tube as shown in FIG. 1 of this invention so as to produce the intended siphonage function and effect. As a result, in such conventional water saving toilets, there is no substantial difference between the water quantity flushed in the water saving stage and that in the full flushing stage, thus resulting in a limited and apparently poor water saving effect; and
2. In conventional water saving toilets, due to the limitation of the single discharging line design employed in the bowl, the amount of the water trap for blocking off the odor from the discharging line must maintain at a level close to the lower edge of the tube under the siphonage start point 2A, that is the point corresponding to the point of the siphonage starting height of the single discharging line at the lower edge point 2B of the tube as shown in FIG. 1 of this invention. With the water trap formed in this manner, the water quantity will be much greater than what is necessary for blocking off the odor in the single discharging line. Therefore, in the process of every full or water saving flushing operation of the conventional water saving toilets, it is necessary to form the water trap with excessive amount of water, thus resulting in considerable waste of water and only limited water saving effect.
From the foregoing, it is apparent that only insignificant water saving effect can be achieved in the water quantity for flushing and water traping with the conventional water saving toilet design. Regarging the total water consumption, conventional water saving toilets do not seem to really serve the water saving purpose.